Identification of Campylobacter jejuni and Campylobacter coli genes contributing to oxidative stress response using TraDIS analysis.

BACKGROUND: Campylobacter jejuni and Campylobacter coli are the major causative agents of bacterial gastroenteritis worldwide and are known obligate microaerophiles. Despite being sensitive to oxygen and its reduction products, both species are readily isolated from animal food products kept under atmospheric conditions where they face high oxygen tension levels. RESULTS: In this study, Transposon Directed Insertion-site Sequencing (TraDIS) was used to investigate the ability of one C. jejuni strain and two C. coli strains to overcome oxidative stress, using H2O2 to mimic oxidative stress. Genes were identified that were required for oxidative stress resistance for each individual strain but also allowed a comparison across the three strains. Mutations in the perR and ahpC genes were found to increase Campylobacter tolerance to H2O2. The roles of these proteins in oxidative stress were previously known in C. jejuni, but this data indicates that they most likely play a similar role in C. coli. Mutation of czcD decreased Campylobacter tolerance to H2O2. The role of CzcD, which functions as a zinc exporter, has not previously been linked to oxidative stress. The TraDIS data was confirmed using defined deletions of perR and czcD in C. coli 15-537360. CONCLUSIONS: This is the first study to investigate gene fitness in both C. jejuni and C. coli under oxidative stress conditions and highlights both similar roles for certain genes for both species and highlights other genes that have a role under oxidative stress.

Monitoring antimicrobial resistance in Campylobacter isolates of chickens and turkeys at the slaughter establishment level across the United States, 2013-2021.

Foodborne infections with antimicrobial-resistant Campylobacter spp. remain an important public health concern. Publicly available data collected by the National Antimicrobial Resistance Monitoring System for Enteric Bacteria related to antimicrobial resistance (AMR) in Campylobacter spp. isolated from broiler chickens and turkeys at the slaughterhouse level across the United States between 2013 and 2021 were analysed. A total of 1,899 chicken-origin (1,031 Campylobacter coli (C. coli) and 868 Campylobacter jejuni (C. jejuni)) and 798 turkey-origin (673 C. coli and 123 C. jejuni) isolates were assessed. Chicken isolates exhibited high resistance to tetracycline (43.65%), moderate resistance to ciprofloxacin (19.5%), and low resistance to clindamycin (4.32%) and azithromycin (3.84%). Turkey isolates exhibited very high resistance to tetracycline (69%) and high resistance to ciprofloxacin (39%). The probability of resistance to all tested antimicrobials, except for tetracycline, significantly decreased during the latter part of the study period. Turkey-origin Campylobacter isolates had higher odds of resistance to all antimicrobials than isolates from chickens. Compared to C. jejuni isolates, C. coli isolates had higher odds of resistance to all antimicrobials, except for ciprofloxacin. The study findings emphasize the need for poultry-type-specific strategies to address differences in AMR among Campylobacter isolates.

The characterization and correlation between the phenotypic and genotypic resistance of Campylobacter spp. isolates from commercial broilers and native chickens in the south of Thailand.

RESEARCH HIGHLIGHTS: High Campylobacter prevalence in chickens; C. jejuni more prevalent than C. coli.Susceptibility to macrolides but resistance to quinolones/tetracyclines in isolates.Homogeneous resistance patterns within farms; higher in broilers than in native birds.Partial association between phenotypic and genotypic resistance among isolates.

Case Commentary: An espresso, a free puppy, and multidrug-resistant Campylobacter.

Campylobacter species infections in immunocompromised patients have the potential to progress to bacteremia and other extra-intestinal diseases. There is a sparsity of robust data, including antibiotic susceptibility data for contemporary agents, upon which to base treatment decisions. Moreover, intrinsic antimicrobial resistance in Campylobacter spp. further limits treatment options. The current publication by Bonilla-Moreno et al. elaborates on this clinical dilemma through the development, treatment, and molecular investigation of the putative mechanisms of carbapenem resistance in an immunocompromised patient with Campylobacter coli bacteremia.

Development of Meropenem Resistance in a Multidrug-Resistant Campylobacter coli Strain Causing Recurrent Bacteremia in a Hematological Malignancy Patient.

Campylobacter bacteremia is an uncommon disease that mainly occurs in immunocompromised patients and is associated with antibiotic resistance, particularly in Campylobacter coli. We report a patient with persistent blood infection because of a multidrug-resistant (MDR) C. coli strain over a 3-month period. Through this period monotherapy with meropenem was associated with the development of resistance to it. Improving immunity status and a combined therapy for intestinal decolonization were useful to control persistent C. coli infection in this patient.

Application of TraDIS to define the core essential genome of Campylobacter jejuni and Campylobacter coli.

Campylobacter species are the major cause of bacterial gastroenteritis. As there is no effective vaccine, combined with the rapid increase in antimicrobial resistant strains, there is a need to identify new targets for intervention. Essential genes are those that are necessary for growth and/or survival, making these attractive targets. In this study, comprehensive transposon mutant libraries were created in six C. jejuni strains, four C. coli strains and one C. lari and C. hyointestinalis strain, allowing for those genes that cannot tolerate a transposon insertion being called as essential. Comparison of essential gene lists using core genome analysis can highlight those genes which are common across multiple strains and/or species. Comparison of C. jejuni and C. coli, the two species that cause the most disease, identified 316 essential genes. Genes of interest highlighted members of the purine pathway being essential for C. jejuni whilst also finding that a functional potassium uptake system is essential. Protein-protein interaction networks using these essential gene lists also highlighted proteins in the purine pathway being major 'hub' proteins which have a large number of interactors across the network. When adding in two more species (C. lari and C. hyointestinalis) the essential gene list reduces to 261. Within these 261 essential genes, there are many genes that have been found to be essential in other bacteria. These include htrB and PEB4, which have previously been found as core virulence genes across Campylobacter species in other studies. There were 21 genes which have no known function with eight of these being associated with the membrane. These surface-associated essential genes may provide attractive targets. The essential gene lists presented will help to prioritise targets for the development of novel therapeutic and preventative interventions.

The potential role of migratory birds in the transmission of pathogenic Campylobacter species to broiler chickens in broiler poultry farms and live bird markets.

BACKGROUND: Campylobacter species (spp.) are one of the most important zoonotic bacteria possessing potential hazards for animal and human health worldwide. Migratory birds are implicated as significant carriers for microbes and a play very important role in the dissemination of Campylobacter to broiler chickens and their environment. The purpose of this investigation was to detect the prevalence, antibiotic resistant patterns, virulence and diversity of pathogenic Campylobacter spp. in 7 migratory bird species (Northern shoveler, Common pochard, Common teal, Northern pintail, Eared Grebe, Great Crested Grebe and Garganey) and broiler chickens that were collected from broiler poultry farms and live bird markets. RESULTS: The prevalence of Campylobacter was 12.5% (25/200), of which 15% (15/100) was recovered from 5 migratory bird species only and 10% (10/100) from broiler chickens. At the level of migratory birds, eight isolates (53.3%) were Campylobacter jejuni (C. jejuni) and 7 isolates (46.7%) were Campylobacter coli (C. coli) meanwhile, in broiler chickens C. jejuni and C. coli were 50% (5/10) for each. All isolated strains had phenotypic resistance to doxycycline, while all of the isolates were susceptible to amikacin. The multidrug resistance to three, four or five antimicrobial classes was found in 72% (18/25) of the isolated strains. The multiantibiotic resistance index between the examined isolates was 0.22-0.77, with 10 antibiotic resistance patterns. The virulence of isolated Campylobacter strains (from both migratory birds and broiler chicken birds) was detected by targeting the VirB11, ciaB and iam genes which were recorded at 16%, 52% and 100%, respectively. Additionally, 100% and 84% of the antibiotic resistance genes were identified as tetA and BlaOXA-61, respectively. CONCLUSIONS: The results of this study revealed the diversity between all the isolated strains from migratory birds and their similarity to broiler chicken isolates. The findings of the present study highlight the impact of migratory birds visiting Egypt and other countries on pathogenic Campylobacter spp. carrying pathogenic virulence and resistance genes, necessitating the application of biosecurity measures to prevent migratory birds from entering farms during their migration period.

Assessing antimicrobial resistance in Campylobacter jejuni and Campylobacter coli and its association with antimicrobial use in Canadian turkey flocks.

Turkeys are important sources of antimicrobial-resistant Campylobacter. A total of 1063 isolates were obtained from 293 turkey flocks across Canada between 2016 and 2021 to evaluate their antimicrobial resistance (AMR) prevalence, patterns, distribution, and association with antimicrobial use (AMU). A high proportion of C. jejuni and C. coli isolates were resistant to tetracyclines and fluoroquinolones, despite the very low use of these drugs. C. jejuni isolates had a higher probability of being resistant to tetracyclines than C. coli isolates. The chance of C. jejuni isolates being resistant to fluoroquinolones, macrolides, and lincosamides was lower compared to C. coli. Isolates from the western region had a higher probability of being resistant to fluoroquinolones than isolates from Ontario. Isolates from Ontario had higher odds of being resistant to tetracyclines than isolates from Quebec. No associations were noted between the resistance and use of the same antimicrobial, but the use of certain antimicrobial classes may have played a role in the maintenance of resistance in Campylobacter (fluoroquinolone resistance - bacitracin and streptogramin use, tetracycline resistance - flavophospholipids and streptogramins use, macrolide resistance - flavophospholipid use). Low-level multidrug-resistant Campylobacter was observed indicating a stable AMR in turkeys. This study provided insights aiding future AMU and AMR surveillance.

Pericarditis due to Campylobacter coli infection: a case report.

Campylobacter spp. is a gram-negative bacillus that causes infectious enteritis and consists of several species, including Campylobacter jejuni, Campylobacter coli, and Campylobacter fetus. Although C. jejuni and C. coli cause infectious enteritis primarily in immunocompetent hosts, C. fetus causes extraintestinal infections such as septicemia, meningitis, and perinatal infections in immunocompromised hosts, as well as myopericarditis in rare cases. Only a few cases of infectious myo(peri)carditis associated with C. coli in immunocompetent hosts have been reported. These studies concentrated on antecedent C. coli enterocolitis and never demonstrated a positive culture in the pericardial fluid.A 72-year-old Japanese man presented with a 2-week fever, cough, and vomiting lasting. He was on hemodialysis for polycystic kidney disease, as well as medication for diabetes and hypertension. A chest computed tomography (CT) scan and a transthoracic echocardiogram revealed bilateral pleural fluid and large pericardial fluid at the time of admission. C. coli was identified from blood culture samples and blood-tinged pericardial fluid. He was successfully treated with antibacterial chemotherapy as well as pericardial fluid drainage and was discharged from the hospital with no complications.In this case, the presence of C. coli in the pericardial fluid confirmed the diagnosis of C. coli pericarditis. C. coli may cause septic pericarditis in immunocompromised hosts, despite typically causing only enteritis.

Inhibitor activity of Lactiplantibacillus plantarum LP5 on thermotolerant campylobacter with different biofilm-forming capacities.

AIMS: To evaluate the biofilm-forming capacity of thermotolerant Campylobacter (TC) strains from poultry production and to analyse the inhibitory capacity of Lactiplantibacillus plantarum LP5 against TC on different materials. METHODS AND RESULTS: Biofilm-forming capacity by Campylobacter jejuni and Campylobacter coli was analysed by cell adhesion in polystyrene plates. TC were classified as non-biofilm-forming (NBF, 1.3%), weak biofilm-forming (WBF, 68.4%), moderate biofilm-forming (MBF, 27.6%), and strong biofilm-forming (SBF, 2.7%). The inhibitory capacity of L. plantarum LP5 against TC was tested on stainless-steel, nylon, aluminium, and glass disks (treated group) and compared with biofilm-forming TC (control group). Lactiplantibacillus plantarum LP5 was inoculated, and then TC. Biofilm was removed in both experimental groups and TC and LP5 bacterial counts were performed. The L. plantarum LP5 presence reduced the formation of TC biofilm (P < 0.001). The material type and strain category influenced biofilm formation, with stainless-steel and the SBF strain being the material and TC having the highest adhesion (P < 0.001). Lactiplantibacillus plantarum LP5 formed a similar biofilm on all materials (P = 0.823). CONCLUSIONS: This trial showed very promising results; L. plantarum LP5 could be incorporated as a bio-protector of TC on different surfaces.

Mining therapeutic targets from the antibiotic-resistant Campylobacter coli and virtual screening of natural product inhibitors against its riboflavin synthase.

Campylobacter coli resides in the intestine of several commonly consumed animals, as well as water and soil. It leads to campylobacteriosis when humans eat raw/undercooked meat or come into contact with infected animals. A common manifestation of the infection is fever, nausea, headache, and diarrhea. Increasing antibiotic resistance is being observed in this pathogen. The increased incidence of C. coli infection, and post-infection complications like Guillain-Barré syndrome, make it an important pathogen. It is essential to find novel therapeutic targets and drugs against it, especially with the emergence of antibiotic-resistant strains. In the current study, genomes of 89 antibiotic-resistant strains of C. coli were downloaded from the PATRIC database. Potent drug targets (n = 36) were prioritized from the core genome (n = 1,337 genes) of this species. Riboflavin synthase was selected as a drug target and pharmacophore-based virtual screening was performed to predict its inhibitors from the NPASS (n = ~ 30,000 compounds) natural product library. The top three docked compounds (NPC115144, NPC307895, and NPC470462) were selected for dynamics simulation (for 50 ns) and ADMET profiling. These identified compounds appear safe for targeting this pathogen and can be further validated by experimental analysis before clinical trials.

Rapid Genotyping of Campylobacter coli Strains from Poultry Meat by PFGE, Sau-PCR, and fla-DGGE.

The genotyping of Campylobacter coli was done using three methods, pulsed-field gel electrophoresis (PFGE), Sau-polymerase chain reaction (Sau-PCR), and denaturing gradient gel electrophoresis assay of flagellin gene (fla-DGGE) and the characteristics of these assays were compared. The results showed that a total of 53 strains of C. coli were isolated from chicken and duck samples in three markets. All isolates were clustered into 31, 33, and 15 different patterns with Simpson's index of diversity (SID) values of 0.972, 0.974, and 0.919, respectively. Sau-PCR assay was simpler, more rapid, and had higher discriminatory power than PFGE assay. Fla-DGGE assay could detect and illustrate the number of contamination types of C. jejuni and C. coli without cultivation, which saved more time and cost than Sau-PCR and PFGE assays. Therefore, Sau-PCR and fla-DGGE assays are both rapid, economical, and easy to perform, which have the potential to be promising and accessible for primary laboratories in genotyping C. coli strains.

Detection of resistance and virulence plasmids in Campylobacter coli and Campylobacter jejuni isolated from North Carolina food animal production, 2018-2019.

Campylobacter remains the leading cause of bacterial foodborne illness in the U.S. and worldwide. Campylobacter plasmids may play a significant role in antimicrobial resistance (AMR) and virulence factor distribution, and potentially drive rapid adaptation. C. coli (n = 345) and C. jejuni (n = 199) isolates collected from live cattle, swine, turkey, and chickens, poultry carcasses at production, and retail meat in N.C. were analyzed to determine plasmid prevalence, extrachromosomal virulence and AMR genes, and the phylogeny of assembled plasmids. Putative plasmids ranging from <2 kb to 237kb were identified with virulence factors present in 66.1% (228/345) C. coli and 88.4% (176/199) C. jejuni plasmids (promoting adherence, invasion, exotoxin production, immune modulation, chemotaxis, mobility, and the type IV secretion system). AMR genes were identified in 21.2% (73/345) C. coli and 28.1% C. jejuni plasmids (conferring resistance to tetracyclines, aminoglycosides, beta-lactams, nucleosides, and lincosamides). Megaplasmids (>100 kb) were present in 25.7% (140/544) of the isolates and carried genes previously recognized to be involved with interspecies recombination. Our study highlights the extensive distribution and diversity of Campylobacter plasmids in food animal production and their role in the dissemination of biomedically important genes. Characterizing Campylobacter plasmids within the food animal production niche is important to understanding the epidemiology of potential emerging strains.

First Report of aac(6')-Ib and aac(6')-Ib-cr Variant Genes Associated with Mutations in gyrA Encoded Fluoroquinolone Resistance in Avian Campylobacter coli Strains Collected in Tunisia.

The aac(6')-Ib gene is the most widespread gene encoding aminoglycoside-modifying enzyme and conferring resistance to tobramycin, streptomycin and kanamycin. The variant aac(6')-Ib-cr gene confers resistance to both aminoglycosides and fluoroquinolones (FQ). A total of 132 Campylobacter isolates, including 91 C. jejuni and 41 C. coli, were selected from broiler hens isolates. The aac(6')-Ib gene was amplified using PCR and was subsequently digested with the BtsCI restriction enzyme to identify aac(6')-Ib-cr. Among these isolates, 31 out of 41 C. coli (75.6%) and 1 (0.98%) C. jejuni were positive for the aac(6')-Ib gene, which was identified as the aac(6')-Ib-cr variant in 10 (32.25%) C. coli isolates. This variant was correlated with mutations in gyrA (Thr-86-Ile), as well as resistance to FQs. This study is the first report in Tunisia on Campylobacter coli strains harboring both the aac(6')-Ib and aac(6')-Ib-cr variants. These genes were present in Campylobacter isolates exhibiting resistance to multiple antibiotics, which restricts the range of available treatments.

Comparison of optical density-based growth kinetics for pure culture Campylobacter jejuni, coli and lari grown in blood-free Bolton broth.

Campylobacter growth kinetic parameters can be used to refine the sensitivity and efficiency of microbial growth-based methods. Therefore, the aim of this study was to construct growth curves for C. jejuni, C. coli, and C. lari in pure culture and calculate growth kinetics for each Campylobacter species in the same environmental conditions. Campylobacter jejuni, C. coli and C. lari were grown over 48 h and inoculated into 15 mL Hungate tubes (N = 3 trials per species; 5 biological replicates per trial; 3 species; 1 strain per species). Absorbance measurements were taken in 45 min intervals over 24 h. Optical density readings were plotted versus time to calculate growth kinetic parameters. C. jejuni exhibited the longest lag phase (p < 0.001) at 15 h 20 min ± 30 min, versus C. coli at 11 h 15 min ± 17 min, and C. lari at 9 h 27 min ± 15 min. The exponential phase duration was no longer than 5 h for all species, and doubling times were all less than 1h 30 min. The variation in growth kinetics for the three species of Campylobacter illustrates the importance of determining individual Campylobacter spp. growth responses for optimizing detection based on low bacterial levels. This study provides kinetics and estimates to define enrichment times necessary for low concentration Campylobacter detection.

Campylobacter jejuni and Campylobacter coli in human stool samples: antibiotic resistance profiles, putative virulence determinants and molecular characterization of the isolates.

Campylobacters, especially C. jejuni and C. coli, have become one of the leading causes of acute gastroenteritis in humans worldwide in recent years. We aimed to investigate the presence, antimicrobial resistance, putative virulence genes, and molecular characterization of C. jejuni and C. coli recovered from human acute gastroenteritis cases in the study. In the study, suspected Campylobacter spp. isolates were obtained in 43 (5%) feces samples collected from a total of 850 patients who applied to the Erciyes University Medical Faculty acute clinic between March 2019 and February 2020. As a result of the phenotypic tests, these isolates were determined to be Campylobacter spp. According to the multiplex PCR, 33 of 43 Campylobacter spp. isolates were identified as C. jejuni (76%) and ten isolates were as C. coli (24%). In the disc diffusion test, the highest resistance rate was found in the trimethoprim/sulfamethoxazole (90.1%) and ciprofloxacin (90.1%), and the lowest rate was found in the amoxicillin-clavulanic acid (9.3%). In Campylobacter spp. isolates, the virulence genes cdtA, virB11, cdtB, cadF, iam, ceu, and flaA were found to be positive at rates of 26 (60%), 28 (65.6%), 13 (30%), 4 (9%), 27 (62%), 17 (39%), and 7 (16%), respectively. However, the cdtC gene was not detected in any of the isolates. The study searched tetO gene to examine the genetic aspect of tetracycline resistance, which was found in all Campylobacter spp. isolates. In the PCR reactions to investigate A2074C and A2075G mutations of macrolide resistance, it was determined as 7 (16%) and 21 (48%) of the isolates. To detect quinolone resistance, the rates of quinolone resistance-determining regions (QRDR) were 20 (45.4%) and the gyrA gene mutations in the mismatch amplification mutation assay PCR (MAMA-PCR), were 19 (43.1%) of isolates. In addition, the quinolone resistance gene (qnr) carried by plasmid in Campylobacter isolates was not found in the study. BlaOXA-61 and CmeB (multi-drug efflux pump) genes were detected as 28 (63.6%) and 30 (68.1), respectively. The Enterobacterial Repetitive Intergenic Consensus PCR (ERIC-PCR) used for typing the isolates revealed that the band profiles obtained from the isolates were different. In conclusion, this was a very comprehensive study revealing the presence of antibiotic-resistant C. jejuni and C. coli with various virulence genes in patients admitted to a university hospital with acute gastroenteritis. This is of utmost significance for public health. Since campylobacteria are foodborne, zoonotic pathogens and transmission occurs mostly through food. People should have detailed information about the transmission routes of campylobacteria and risky foods. In addition, staff, food processors and caterers, should be trained in hygiene.

[Prevalence and Antimicrobial Resistance of Campylobacter jejuni/coli and Analysis of Macrolide Resistance Isolates from Retail Meat in Tokyo, Japan (2010-2019)].

This study aimed to investigate the prevalence and antimicrobial sensitivity of Campylobacter jejuni and Campylobacter coli in retail meat (chicken, beef, pork, venison, wild boar, horse, lamb and mutton) in Tokyo (Japan) from 2010 to 2019. Furthermore, the resistance mechanism of erythromycin (EM)-resistant strains was analysed. C. jejuni had a highly positive rate in domestic chicken meat (53.4%, 334/626 samples), domestic chicken offal (49.3%, 34/69 samples), and domestic beef offal (28.3%, 47/166 samples), while C. coli had a high positivity rate in domestic pork offal (31.7%, 44/139 samples). The positive rate of C. jejuni was significantly higher in offal than that in meat in domestic beef, while the positive rate of C. coli was significantly higher in offal than that in meat in domestic beef and domestic pork (p<0.05). In the isolates, 1.0% (6/631 strains) of C. jejuni and 36.2% (55/152 strains) of C. coli were EM resistant, with 41.5% (262/631 strains) of C. jejuni and 65.1% (99/152 strains) of C. coli being ciprofloxacin resistant. A2075G mutation of the 23S rRNA gene was confirmed in all EM-resistant strains.

Genomic Screening of Antimicrobial Resistance Markers in UK and US Campylobacter Isolates Highlights Stability of Resistance over an 18-Year Period.

Campylobacter jejuni and Campylobacter coli are important bacterial causes of human foodborne illness. Despite several years of reduced antibiotics usage in livestock production in the United Kingdom (UK) and United States (US), a high prevalence of antimicrobial resistance (AMR) persists in Campylobacter. Both countries have instigated genome sequencing-based surveillance programs for Campylobacter, and in this study, we have identified AMR genes in 32,256 C. jejuni and 8,776 C. coli publicly available genome sequences to compare the prevalence and trends of AMR in Campylobacter isolated in the UK and US between 2001 and 2018. AMR markers were detected in 68% of C. coli and 53% of C. jejuni isolates, with 15% of C. coli isolates being multidrug resistant (MDR), compared to only 2% of C. jejuni isolates. The prevalence of aminoglycoside, macrolide, quinolone, and tetracycline resistance remained fairly stable from 2001 to 2018 in both C. jejuni and C. coli, but statistically significant differences were observed between the UK and US. There was a statistically significant higher prevalence of aminoglycoside and tetracycline resistance for US C. coli and C. jejuni isolates and macrolide resistance for US C. coli isolates. In contrast, UK C. coli and C. jejuni isolates showed a significantly higher prevalence of quinolone resistance. Specific multilocus sequence type (MLST) clonal complexes (e.g., ST-353/464) showed >95% quinolone resistance. This large-scale comparison of AMR prevalence has shown that the prevalence of AMR remains stable for Campylobacter in the UK and the US. This suggests that antimicrobial stewardship and restricted antibiotic usage may help contain further expansion of AMR prevalence in Campylobacter but are unlikely to reduce it in the short term.

Antimicrobial Resistance in Campylobacter coli and Campylobacter jejuni from Human Campylobacteriosis in Taiwan, 2016 to 2019.

Campylobacter coli and Campylobacter Jejuni are highly resistant to most therapeutic antimicrobials in Taiwan; rapid diagnostics of resistance in bacterial isolates is crucial for the treatment of campylobacteriosis. We characterized 219 (40 C. coli and 179 C. jejuni) isolates recovered from humans from 2016 to 2019 using whole-genome sequencing to investigate the genetic diversity among isolates and the genetic resistance determinants associated with antimicrobial resistance. Susceptibility testing with 8 antimicrobials was conducted to assess the concordance between phenotypic resistance and genetic determinants. The conventional and core genome multilocus sequence typing analysis revealed diverse clonality among the isolates. Mutations in gyrA (T86I, D90N), rpsL (K43R, K88R), and 23S rRNA (A2075G) were found in 91.8%, 3.2%, and 6.4% of the isolates, respectively. The horizontally transferable resistance genes ant(6)-I, aad9, aph(3')-IIIa, aph(2″), blaOXA, catA/fexA, cfr(C), erm(B), lnu, sat4, and tet were identified in 24.2%, 21.5%, 33.3%, 11.9%, 96.3%, 10.0%, 0.9%, 6.8%, 3.2%, 13.2%, and 96.3%, respectively. High-level resistance to 8 antimicrobials in isolates was 100% predictable by the known resistance determinants, whereas low-level resistance to azithromycin, clindamycin, nalidixic acid, ciprofloxacin, and florfenicol in isolates was associated with sequence variations in CmeA and CmeB of the CmeABC efflux pump. Resistance-enhancing CmeB variants were identified in 62.1% (136/219) of isolates. In conclusion, an extremely high proportion of C. coli (100%) and C. jejuni (88.3%) were multidrug-resistant, and a high proportion (62.5%) of C. coli isolates were resistant to azithromycin, erythromycin, and clindamycin, which would complicate the treatment of invasive campylobacteriosis in this country.

Telithromycin resistance in Campylobacter mediated by 23S rRNA A2075G mutation and erm(B).

OBJECTIVES: Recently, epidemiological research has shown an unusually high prevalence of telithromycin-resistant Campylobacter. This study was designed to investigate the potential resistance mechanism of telithromycin resistance in Campylobacter. METHODS: A total of 122 Campylobacter isolates of chicken origin collected in 2019 from three regions of China were tested for susceptibility to telithromycin. The potential mechanism of resistance to telithromycin in Campylobacter was revealed through WGS analysis and natural transformation. RESULTS: In this study, 51.3% (61/119) of Campylobacter coli and 100.0% (3/3) of Campylobacter jejuni were resistant to telithromycin. erm(B) or A2075G mutation in 23S rRNA (23S_A2075G) was identified in the telithromycin-resistant C. coli. Cloning of the erm(B) or 23S_A2075G into C. jejuni NCTC 11168 resulted in a 256-fold increase in the MIC of telithromycin. MLST results indicated that various STs were involved in the dissemination of 23S_A2075G and erm(B). Phylogenetic analysis showed that the C. coli isolates with 23S_A2075G and erm(B) from chickens and humans were closely related. CONCLUSIONS: 23S_A2075G and erm(B), which have been widely spread in different genotypes of C. coli isolated from animals and humans, could mediate high levels of resistance to telithromycin in C. coli. C. coli containing 23S_A2075G or erm(B) are clonally related and have the potential to spread zoonotic diseases.